Pmp-like proteins Pls1 and Pls2 are secreted into the lumen of the Chlamydia trachomatis inclusion
Pmp-like proteins Pls1 and Pls2 are secreted into the lumen of the Chlamydia trachomatis inclusion
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DOI：
10.1128/iai.00632-08
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发表时间：
2008-09-01
影响因子：
3.1
通讯作者：
Valdivia, Raphael H.
中科院分区：
文献类型：
--
作者：
Jorgensen, Ine;Valdivia, Raphael H.
专性细胞内病原体沙眼衣原体分泌效应蛋白跨越含病原体的空泡（内含物）的膜来调节宿主细胞功能。在分泌衣原体蛋白的免疫学筛选中，我们确定CT 049和CT 050为潜在的包涵体膜相关蛋白。这些酸性非小叶蛋白与多态性膜蛋白PmpC的乘客结构域旁系同源，并且像其他Pmp蛋白一样，在C.沙眼眼和泌尿生殖系菌株。我们产生了这些Pmp样分泌（PLS）蛋白的抗体，并通过免疫荧光显微镜确定，PLS 1（CT 049）和PLS 2（CT 050）定位于包涵体内腔和包涵体膜内的球状结构。通过差速离心和密度梯度离心分离感染细胞的膜和细胞质组分进一步表明，Pls 1和Pls 2与不同于大量细菌和包涵体膜的膜相关。Pls 1的积累，并在较小程度上，Pls 2在包涵体腔是不敏感的III型分泌抑制剂C1，这表明这种易位系统是不是必不可少的Pls蛋白分泌。相比之下，Pls分泌和稳定性对低水平的β-内酰胺抗生素敏感，表明从细菌细胞分泌Pls需要功能性细胞壁。最后，我们通过显微注射抗Pls 1和抗Pls 2抗体到受感染的细胞中来测试衣原体感染对这些蛋白质的需求。共注射抗-Pls 1和-Pls 2抗体部分抑制了包涵体的扩张。由于Pls蛋白缺乏经典的sec依赖的分泌信号，我们建议，Pls蛋白分泌到包涵体腔的一种新的机制，以调节重要的衣原体复制和包涵体扩张的事件。
The obligate intracellular pathogen Chlamydia trachomatis secretes effector proteins across the membrane of the pathogen-containing vacuole (inclusion) to modulate host cellular functions. In an immunological screen for secreted chlamydial proteins, we identified CT049 and CT050 as potential inclusion membrane-associated proteins. These acidic, nonglobular proteins are paralogously related to the passenger domain of the polymorphic membrane protein PmpC and, like other Pmp proteins, are highly polymorphic among C. trachomatis ocular and urogenital strains. We generated antibodies to these Pmp-like secreted (Pls) proteins and determined by immunofluorescence microscopy that Pls1 (CT049) and Pls2 (CT050) localized to globular structures within the inclusion lumen and at the inclusion membrane. Fractionation of membranes and cytoplasmic components from infected cells by differential and density gradient centrifugation further indicated that Pls1 and Pls2 associated with membranes distinct from the bulk of bacterial and inclusion membranes. The accumulation of Pls1 and, to a lesser extent, Pls2 in the inclusion lumen was insensitive to the type III secretion inhibitor C1, suggesting that this translocation system is not essential for Pls protein secretion. In contrast, Pls secretion and stability were sensitive to low levels of beta-lactam antibiotics, suggesting that a functional cell wall is required for Pls secretion from the bacterial cell. Finally, we tested the requirement for these proteins in Chlamydia infection by microinjecting anti-Pls1 and anti-Pls2 antibodies into infected cells. Coinjection of anti-Pls1 and -Pls2 antibodies partially inhibited expansion of the inclusion. Because Pls proteins lack classical sec-dependent secretion signals, we propose that Pls proteins are secreted into the inclusion lumen by a novel mechanism to regulate events important for chlamydial replication and inclusion expansion.